Province dam on brink of failure

A 3-foot section of a dam on a Province lake began to fail Friday. Photo by Jon L. Wilson

The spillway dam on the lake at Province began to fail Friday morning as a 30-foot wide piece washed away.

A crew with Rain for Rent from Chandler quickly set up a large water pump to lower the level of the lake, in an attempt to stop a complete breech of the dam. The pump was turned on shortly before 2 p.m. Friday.

“The Province basin was overtopped due to the storm event,” said Dan Frank, president of Maricopa Flood Control District and Civil Engineer. “We had a little larger storm than we would expect to see. The lake is designed to overflow the top in that location. For some reason the soil that’s supporting the gavions, the rock baskets, on the edge of the lake failed and eroded during the event. That caused a failure of the gavion basket structure – the soil between the gavions and the lake itself.”

He said the lake is designed to take on storm water from all over the community. Thursday night and Friday morning the lake overflowed as 1.07 inches of rain fell in the area.

Frank said a crew is attempting to lower the lake, stopping to overflow of the spillway and allowing crews to backfill and do repairs.

“They want to drain the lake down somewhat,” Frank said. “They need to do that to stop the erosion and to get in where the failure is and repair it safely. So, they are not at risk of having a blowout of the lake liner, while they are making the repair.”

Frank said earlier Friday morning there was concern about losing the entire spillway.

“That’s when we decided it would be prudent to drain the lake down as much as we can. We don’t want to drain it down all the way,” Frank said.

He said he was contacted by the City of Maricopa about the spillway failure about 9:30 a.m. Friday

“The plan is to get the lake drained down, so they can safely work on it. They’re going to fix the hole by back filling it with better compacted material and try to improve the spillway somewhat,” Frank said.

If the spillway were to fail the lake’s water would spill directly into the Santa Rosa Wash, where it intersects Smith-Enke Road. The Rain for Rent pumps are lowering the lake level by directly pumping it into the wash.